In recent years there has come about a demand for a reduced-size substation, and this demand, on the part of public utilities, has been net by gas-insulated substation equipment, such as set forth in U.S. Pat. Nos. 3,378,731, Whitehead; 3,348,001, Upton et al.; 3,801,768, Meyer; 3,794,797, Spindle et al.; 3,356,798, McKinnon; 3,610,858, Gruber et al.; 3,599,041, Boersma et al; and 3,562,460, Koener.
The foregoing equipment significantly reduces the space required by the high-voltage side of substations rated, for example, 115 through 345 K.V. The space reduction is accomplished by replacing the open bus and air-type terminal-bushings with gas-insulated bus, filled, for example, with a highly-insulating gas, such as sulfur-hexafluoride (SF.sub.6) gas, at a pressure say, for example, 45 p.s.i.g., and thereby permitting the location of electrical equipment very close together. This gas-insulated substation equipment has many advantages, among which are:
1. Significant reduction in space requirements both in land area and overall height. PA1 2. Added system reliability by eliminating the possibility of phase-to-phase faults, lightning strokes within the system, or contamination of insulators. PA1 3. Reduced maintenance because the closed system is isolated from its environment. PA1 4. Added personnel safety because all live parts are covered by grounded shields. PA1 5. The gas-insulated modular approach has the additional advantage, because it provides the utility user with lower installation costs, when compared with conventional, or other types of power-transmission systems.